This invention concerns the addition of pretreated inorganic particulates to a cementitious product to improve the product's strength properties and its resistance to water absorption and penetration.
It is well known that an increase in strength and a reduction in water absorption and permeability are desirable for cementitious products because of the increased durability that results. Among prior attempts at such property improvements is the use of additives, including fatty acids, to such products, which often contain other components, including limestone. For example, U.S. Pat. No. 4,375,987 discloses a water-dispersible additive for imparting water repellency to masonary cement, the cement being interground in the presence of the additive, which includes a fatty acid, plus other ingredients such as limestone. In Japanese Kokai 95657/80, an agent for addition to a waterproofing coating for concrete is prepared by reacting stearic acid with slaked lime and mica, and the resulting calcium stearate is blended with a dehydrating agent and other ingredients, including limestone, to form the coating.
Despite the many prior attempts at improving strength and water resistance of cement products, more effective means are constantly being sought. It is the primary objective of the present invention to provide such a means.
In Japanese Kokai 100180/82, a thickener such as calcium carbonate is added to cement milk, which may include a small amount of a fatty acid, to increase the viscosity of the cement milk.
The addition of fatty acid treated limestone to plastics for improving properties is disclosed, for example, in U.S. Pat. Nos. 4,278,576 and 4,444,921.